Differential Adsorption of l‐ and d‐Lysine on Achiral MFI Zeolites as Determined by Synchrotron X‐Ray Powder Diffraction and Thermogravimetric Analysis

Reported here is the first crystallographic observation of stereospecific bindings of l‐ and d‐lysine (Lys) in achiral MFI zeolites. The MFI structure offers inherent geometric and internal confinement effects for the enantiomeric difference in l‐ and d‐Lys adsorption. Notable differences have been observed by circular dichroism (CD) spectroscopy and thermogravimetric analysis (TGA). Distinct l‐ and d‐Lys adsorption behaviours on the H‐ZSM‐5 framework have been revealed by the Rietveld refinement of high‐resolution synchrotron X‐ray powder diffraction (SXRD) data and the density‐functional theory (DFT) calculations. Despite demonstrating the approach for l‐ and d‐Lys over MFI zeolites at an atomistic resolution, the differential adsorption study sheds light on the rational engineering of molecular interaction(s) with achiral microporous materials for chiral separation purposes. Behavioural differences: Differential adsorption behaviour of l‐ and d‐Lys over H‐ZSM‐5 has been observed experimentally by circular dichroism spectroscopy and thermogravimetric analyses. The fundamental reason is explained by structural studies based on SXRD data and the DFT calculations.